1. Field of the Invention
The present embodiment of the invention relates to a distance determination and alarm system for use in connection with alarm systems. The distance determination and alarm system has particular utility in connection with alarm systems that can be switched between alarming for proximal and distal distances.
2. Description of the Prior Art
Distance determination and alarm systems are desirable for being able to be warned if a transmitter is exceeding a specific distance to prevent loss. A need was felt for a switchable distance determination and alarm system that could be set to alarm when distances are being exceeded or whenever the transmitter is proximate to the receiver.
The use of alarm systems is known in the prior art. For example, U.S. Pat. No. 5,589,821 to Sallen et al. discloses a distance determination and alarm system generates an alarm at one unit of the system when a second unit of the system is more than a predetermined distance from the first unit. The system has a first transceiver unit with a first transmitter for transmitting a first reference signal having a phase with respect to a reference source, and a first receiver for detecting a second reference signal having a phase which bears a relationship to that of the first reference signal. There is a second, portable, transceiver unit with a second transmitter for transmitting the second reference signal after receipt of the first reference signal. The first transceiver unit includes a distance resolver for determining the distance between the two transceiver units from the phases of the first and second reference signals, and an alarm, responsive to the distance resolver, for generating an alarm signal if the distance between the two transceiver units is more than a predetermined amount. However, the Sallen et al. '821 patent does not have the ability to switch between preferential distal or proximate transmitter to receiver distances.
Similarly, U.S. Pat. No. 6,366,202 to Rosenthal discloses a paired lost item finding system including at least two nearly identical locators. Either one can be used to find the other and whatever items are attached to it. In the preferred embodiment, acoustic signals near 6500 Hz are used to broadcast a search signal from an available locator to a lost one. Preferably, the search signal includes a sequences of tones having predetermined frequency differences between them. The lost locator is usually in a sleep mode, in which it nonetheless is capable of recognizing the beginning of the search signal. The locator turns on to an active mode in which it consumes more power. It determines the baseline frequency and then identifies whether the signal it is receiving conforms to the predetermined frequency differences between the sequence of tones. If it does, the lost locator transmits a beacon signal that can be perceived by the user as he searches for the lost item. The beacon signal may include both an audible signal and a flashing light emitting diode. Another feature allows the number of false alarms to be reduced, particularly in a noisy environment, but also allows the locators to be operable in a noisy environment. Yet further capabilities include the selection of baseline frequencies or the temporary deactivation of additionally available locators. Advantageously, both the transmission and reception of the audio signal is accomplished with one piezoelectric transducer, and the efficiency of the transducer is increased by forming a resonant cavity having a cap both protecting the piezoelectric transducer and forming a side emitting annular port. However, the Rosenthal '202 patent does not have the ability to switch between preferential distal or proximate transmitter to receiver distances.
Likewise, U.S. Pat. No. 5,576,692 to Tompkins et al. discloses a nationwide airport luggage tracking system for tracking luggage pieces in any airport across a wide geographic area involves the attaching of a beeper paging unit to each luggage piece and causing any selected beeper units to beep wherever located in a geographic area served by a paging system. However, the Tompkins et al. '692 patent does not have the ability to switch between preferential distal or proximate transmitter to receiver distances.
Further, U.S. Pat. No. 4,101,873 to Anderson et al. discloses a device to locate commonly misplaced objects has miniaturized coded transmitter and battery powered receivers selectively responsive to a predetermined code transmission are provided with a miniaturized audible signal generator in each receiver such that the receiver, when interrogated by a proper signal, will respond audibly. By placing such receivers on commonly used objects such as eyeglasses, purses and other personal articles, audible location of these articles is accomplished by interrogating each object with a corresponding coded signal and following the audible response from the object to the position of the object to locate the latter. The duty cycle of the receiver is very short and recurrent over intervals less than the known energization interval of the transmitter to insure reception but materially minimize the power consumption of the receivers. However, the Anderson et al. '873 patent does not have the ability to switch between preferential distal or proximate transmitter to receiver distances.
Still further, U.S. Pat. No. Des. 339,757 to Feeney discloses a combined transmitter and receiver for a child locator. However, the Feeney '757 patent does not have the ability to switch between preferential distal or proximate transmitter to receiver distances.
Lastly, U.S. Pat. No. 6,198,930 to Schipper discloses a system for tracking the location of, and for providing cellular telephone handoff for, a mobile cell phone user as the cell phone user moves from one cell zone to another. A boundary curve between a first cell zone and an adjacent second cell zone is defined in an electronic map by an equation for points with spatial location coordinates lying on the curve. First and second quasi-boundary curves, lying within the first and second cell zones, respectively, are defined, where each point on the curve lies at a selected distance from the boundary curve. A region of points lying between the quasi-boundary curves and including the boundary curve is defined. The present location of the cell phone user is determined using a Satellite Positioning System (SATPS) such as GPS or GLONASS. Cellular telephone service for the cell phone user is provided by a first cellular service provider or by a second cellular service provider, when the cell phone user is located within the first cell zone, not including the overlap region within the second cell zone. When the cell phone user enters the region from within the first cell zone and proceeds toward the boundary curve, the system carried by the cell phone user notifies at least one of the first and second cellular service providers that the cell phone user is about to leave the first cell zone and about to enter the second cell zone. The system may be extended to determine the approximate location of a missing vehicle and to dynamically change the boundary curves of at least one cell zone to relieve cellular service overloading that occurs within that cell zone. However, the Schipper '930 patent does not have the ability to switch between preferential distal or proximate transmitter to receiver distances.
While the above-described devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not describe a distance determination and alarm system that allows alarm systems that can be switched between alarming for proximal and distal distances. The Sallen et al. '821, Rosenthal '202, Tompkins et al. '692, Anderson et al. '873, Feeney '757 and Schipper '930 patents make no provision for the ability to switch between preferential distal or proximate transmitter to receiver distances.
Therefore, a need exists for a new and improved distance determination and alarm system which can be used for alarm systems that can be switched between alarming for proximal and distal distances. In this regard, the present embodiment of the invention substantially fulfills this need.
In this respect, the distance determination and alarm system according to the present embodiment of the invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of alarm systems that can be switched between alarming for proximal and distal distances.